Scleral prosthesis for treatment of presbyopia and other eye disorders

ABSTRACT

Presbyopia is treated by implanting within a plurality of elongated pockets formed in the tissue of the sclera of the eye transverse to a meridian of the eye, a prosthesis having an elongated body having a first surface and a second surface opposite the first surface to contact the base and flap of the scleral pocket. The first and second surfaces are spaced apart a distance so that the implanted prosthesis exerts an outward force on the flap of the scleral pocket which results in an outward traction on at least the anterior margin of the scleral pocket. The combined effect of the implanted prostheses is to exert a radially outward traction on the sclera in the region overlying the ciliary body which expands the sclera in the affected region together with the underlying ciliary body. The expansion of the ciliary body restores the effective working distance of the ciliary muscle in the presbyopic eye and thereby increases the amplitude of accommodation. Hyperopia, primary open angle glaucoma and/or ocular hypertension can be treated by increasing the effective working distance of the ciliary muscle according to the invention. A preferred embodiment of the scleral prosthesis has a major surface adapted to contact the base or flap of the pocket and an opposite surface or ridge spaced from the major surface.

RELATIONSHIP TO OTHER APPLICATIONS

This application is a continuation of prior U.S. application Ser. No.09/061,168 filed on Apr. 16, 1998, which issued as U.S. Pat. No.6,280,468 on Aug. 28, 2001, which is a continuation-in-part of priorU.S. application Ser. No. 08/946,975 filed on Oct. 8, 1997, which issuedas U.S. Pat. No. 6,007,578 on Dec. 28, 1999.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to methods of treating presbyopia, hyperopia,primary open angle glaucoma and ocular hypertension and moreparticularly to methods of treating these diseases by increasing theeffective working distance of the ciliary muscle. The invention alsorelates to increasing the amplitude of accommodation of the eye byincreasing the effective working range of the ciliary muscle.

2. Brief Description of the Prior Art

In order for the human eye to have clear vision of objects at differentdistances, the effective focal length of the eye must be adjusted tokeep the image of the object focused as sharply as possible on theretina. This change in effective focal length is known as accommodationand is accomplished in the eye by varying the shape of the crystallinelens. Generally, in the unaccommodated emmetropic eye the curvature ofthe lens is such that distant objects are sharply imaged on the retina.In the unaccommodated eye near objects are not focused sharply on theretina because their images lie behind the retinal surface. In order tovisualize a near object clearly, the curvature of the crystalline lensis increased, thereby increasing its refractive power and causing theimage of the near object to fall on the retina.

The change in shape of the crystalline lens is accomplished by theaction of certain muscles and structures within the eyeball or globe ofthe eye. The lens is located in the forward part of the eye, immediatelybehind the pupil. It has the shape of a classical biconvex optical lens,i.e., it has a generally circular cross section having two convexrefracting surfaces, and is located generally on the optical axis of theeye, i.e., a straight line drawn from the center of the cornea to themacula in the retina at the posterior portion of the globe. In theunaccommodated human eye the curvature of the posterior surface of thelens, i.e., the surface adjacent to the vitreous body, is somewhatgreater than that of the anterior surface. The lens is closelysurrounded by a membranous capsule that serves as an intermediatestructure in the support and actuation of the lens. The lens and itscapsule are suspended on the optical axis behind the pupil by a circularassembly of very many radially directed elastic fibers, the zonules,which are attached at their inner ends to the lens capsule and at theirouter ends to the ciliary muscle, a muscular ring of tissue, locatedjust within the outer supporting structure of the eye, the sclera. Theciliary muscle is relaxed in the unaccommodated eye and thereforeassumes its largest diameter. According to the classical theory ofaccommodation, originating with Helmholtz, the relatively large diameterof the ciliary muscle in this condition causes a tension on the zonuleswhich in turn pulls radially outward on the lens capsule, causing theequatorial diameter of the lens to increase slightly and decreasing theanterior-posterior dimension of the lens at the optical axis. Thus, thetension on the lens capsule causes the lens to assume a flattened statewherein the curvature of the anterior surface, and to some extent theposterior surface, is less than it would be in the absence of thetension. In this state the refractive power of the lens is relativelylow and the eye is focused for clear vision for distant objects.

When the eye is intended to be focused on a near object, the ciliarymuscles contract. According to the classical theory, this contractioncauses the ciliary muscle to move forward and inward, thereby relaxingthe outward pull of the zonules on the equator of the lens capsule. Thisreduced zonular tension allows the elastic capsule of the lens tocontract causing an increase in the antero-posterior diameter of thelens (i.e., the lens becomes more spherical) resulting in an increase inthe optical power of the lens. Because of topographical differences inthe thickness of the lens capsule, the central anterior radius ofcurvature decreases more than the central posterior radius of curvature.This is the accommodated condition of the eye wherein the image of nearobjects falls sharply on the retina.

Presbyopia is the universal decrease in the amplitude of accommodationthat is typically observed in individuals over 40 years of age. In theperson having normal vision, i.e., having emmetropic eyes, the abilityto focus on near objects is gradually lost, and the individual comes toneed glasses for tasks requiring near vision, such as reading.

According to the conventional view the amplitude of accommodation of theaging eye is decreased because of the loss of elasticity of the lenscapsule and/or sclerosis of the lens with age. Consequently, even thoughthe radial tension on the zonules is relaxed by contraction of theciliary muscles, the lens does not assume a greater curvature. Accordingto the conventional view, it is not possible by any treatment to restorethe accommodative power to the presbyopic eye. The loss of elasticity ofthe lens and capsule is seen as irreversible, and the only solution tothe problems presented by presbyopia is to use corrective lenses forclose work, or bifocal lenses, if corrective lenses are also requiredfor distant vision.

Certain rings and/or segments have been used in ocular surgery forvarious purposes. Rings and/or segments of flexible and/or elasticmaterial, attached or prepared in situ by fastening the ends of stripsof the material around the posterior portion of the globe, posterior tothe pars plana (over the underlying retina), have been used to compressthe sclera in certain posterior regions. Supporting rings of metal,adapted to fit the contour of the sclera have been used as temporarysupporting structures during surgery on the globe. However, none ofthese known devices have been used for surgical treatment of presbyopia,and none have been adapted to the special needs of prosthetic devicesused in treating presbyopia.

Accordingly, a need has continued to exist for a method of treatingpresbyopia that will increase the amplitude of accommodation of thepresbyopic eye, thereby lessening or eliminating the need for auxiliaryspectacle lenses to relieve the problems of presbyopia.

SUMMARY OF THE INVENTION

The treatment of presbyopia has now been facilitated by the prostheticdevice of this invention which is implanted within a pocket formedwithin the tissue of the sclera of the globe of the eye in a zone of thesclera in the vicinity of the plane of the equator of the crystallinelens. The scleral pocket is formed by tunnelling through the tissue ofthe sclera in a circumferential direction in the defined zone of theglobe. The scleral pocket thus has a base formed by the sclera tissuelying inward of the pocket, i.e., toward the interior of the globe, anda flap formed from the tissue located outward of the pocket. The scleralpocket accordingly resembles a belt loop. The prosthetic device of theinvention comprises an elongated body having a first surface and asecond surface opposite the first surface, the surfaces being adapted tocontact the base and flap of the scleral pocket. The first and secondsurfaces are spaced apart a distance such that, when the prosthesis isimplanted in the scleral pocket its opposed surfaces separate the baseand flap of the scleral pocket thereby applying an outward force on theflap which results in an outward traction on at least the anteriormargin of the scleral pocket. This traction elevates the portion of thesclera at the margin of the pocket and the ciliary body immediatelybeneath the sclera and attached thereto. This outward movement of theciliary body increases the working distance of the ciliary musclethereby allowing it to exert an increased force on the equator of thecrystalline lens through the zonules. Preferably the prosthesis has anelongated planform and the first surface of the prosthesis is a majorsurface adapted to contact the base or flap of the scleral pocket. Thesecond surface may be a relatively broad surface or a relatively narrowridge extending along the planform of the prosthesis.

Accordingly, it is an object of the invention to provide a treatment forpresbyopia.

A further object is to provide a treatment for presbyopia by increasingthe effective working distance of the ciliary muscle in the presbyopiceye.

A further object is to provide a treatment for presbyopia by increasingthe radial distance between the equator of the crystalline lens and theciliary body.

A further object is to provide a treatment for presbyopia by implantingin the sclera a plurality of prostheses which will increase the workingdistance of the ciliary muscle.

A further object is to provide a prosthesis for implanting in the scleraof an eye that will increase the working distance of the ciliary muscle.

A further object is to provide a prosthesis for implanting in the scleraof an eye that will expand the sclera in the zone of the sclerasurrounding the ciliary body.

A further object is to provide a prosthesis for implanting in the scleraof an eye that will increase the diameter of the ciliary body generallyin the equatorial plane of the crystalline lens.

A further object is to provide a treatment for hyperopia.

A further object is to provide a treatment for primary open angleglaucoma.

A further object is to provide a treatment for ocular hypertension.

A further object is to provide a treatment for increasing the amplitudeof accommodation of the eye.

Further objects of the invention will become apparent from thedescription of the invention which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an isometric view of an eye having the prosthesis of thisinvention implanted therein.

FIG. 2 shows a front elevational view of an eye showing the location ofstraight scleral pockets.

FIG. 3 shows a front elevational view of an eye showing the location ofstraight scleral pockets.

FIG. 4 shows a cross section of the eye of FIG. 2 along the line 4-4.

FIG. 5 shows an enlarged view of the cross section of FIG. 4 in theregion indicated by the circle 5.

FIG. 6 shows a plan view of a rectangular embodiment of the prosthesisof the invention having a flat base.

FIG. 7 shows a front elevational view of the prosthesis illustrated inFIG. 6.

FIG. 8 shows an end elevational view of the prosthesis shown in FIG. 6.

FIG. 9 shows a plan view of an embodiment of the prosthesis that iscurved in the plane of the base.

FIG. 10 shows an end view of the prosthesis of FIG. 9.

FIG. 11 illustrates a plan view of an alternate embodiment of theprosthesis of the invention.

FIG. 12 shows a front elevational view of the prosthesis illustrated inFIG. 11.

FIG. 13 shows an end elevational view of the prosthesis of FIG. 11.

FIG. 14 illustrates a plan view of an embodiment of the invention inwhich the ridge member extends beyond the end of the base member.

FIG. 15 shows a front elevational view of the prosthesis illustrated inFIG. 14.

FIG. 16 a shows an end elevational view of the prosthesis of FIG. 14,wherein the base prosthesis is tapered to the posterior edge.

FIG. 16 b shows an end elevational view of a prosthesis similar to thatshown in FIGS. 14, 15 and 16 a, wherein the base is not tapered.

FIG. 17 shows a plan view of an embodiment of the prosthesis of theinvention wherein the prosthesis is hollow and made of an elastomericmaterial that is filled with a liquid.

FIG. 18 shows a front elevational view of the prosthesis illustrated inFIG. 17.

FIG. 19 shows a cross sectional view of the prosthesis of FIG. 17 alongthe line 19-19.

FIG. 20 shows an end elevational view of the prosthesis of FIG. 17.

FIG. 21 illustrates a plan view of an embodiment of the prosthesis ofthe invention wherein the base is curved to match the curvature of theglobe.

FIG. 22 shows a front elevational view of the prosthesis illustrated inFIG. 21.

FIG. 23 shows an end elevational view of the prosthesis of FIG. 21.

FIG. 24 illustrates a plan view of an alternate embodiment of theprosthesis of the invention having a curved surface adapted to contactthe base of the scleral pocket.

FIG. 25 shows a front elevational view of the prosthesis illustrated inFIG. 24.

FIG. 26 shows an end elevational view of the prosthesis of FIG. 24.

FIG. 27 shows a cross-section of the prosthesis shown in FIG. 24 alongthe line 27-27.

FIG. 28 shows a front elevational view of an eye having four prosthesesof the type illustrated in FIGS. 24-27 implanted in the sclera thereof.

FIG. 29 shows a cross section of the eye of FIG. 28 along the line29-29.

FIG. 30 shows an enlarged view of the cross section of FIG. 29 in theregion indicated by the circle 30.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS

This invention is based on a different theory, developed by theinventor, which has been described in U.S. Pat. No. 5,354,331, theentire disclosure of which is incorporated herein by reference,regarding the cause of the loss of amplitude of accommodation thatconstitutes presbyopia. According to the invention, presbyopia istreated by increasing the effective working distance of the ciliarymuscle. This is accomplished by increasing the distance between theciliary muscle and the lens equator by increasing the diameter of thesclera in the region of the ciliary body.

According to the invention the effective working distance of the ciliarymuscle is increased by implanting in pockets surgically formed in thesclera of the eye a plurality of prostheses designed to place an outwardtraction on the sclera in the region of the ciliary body. The relevantanatomy of the eye for locating the scleral pockets may be seen byreference to FIGS. 1-4. The outermost layer of the eye 100 comprises thewhite, tough sclera 102 which encompasses most of the globe and thetransparent cornea 104, which constitutes the anterior segment of theouter coat. The circular junction of the cornea and sclera is the limbus106. Within the globe of the eye, as illustrated in the cross-section ofFIG. 4, the crystalline lens 108 is enclosed in a thin membranouscapsule and is located immediately posterior to the iris 112, suspendedcentrally posterior to the pupil 114 on the optical axis of the eye. Thelens 108 is suspended by zonules extending between the lens capsule atthe equator 110 of the lens 108 and the ciliary body 116. The ciliarybody 116 lies just under the sclera 102 (i.e., just inwardly of thesclera 102) and is attached to the inner surface of the sclera 102. Asmay be seen in FIG. 4, the ciliary body 116 lies generally in a plane130 defined by the equator 110 of the lens 108. The plane 130 can alsobe extended to intersect the sclera 102 whereby it forms a generallycircular intersection located about 2 millimeters posterior to thelimbus 106. The external muscles 118 of the eyeball control the movementof the eye.

According to the invention a generally outwardly directed traction isexerted on the sclera in the region of the ciliary body to expand thesclera 102 in that region. This expansion of the sclera 102 produces acorresponding expansion of the attached ciliary body 116 and moves theciliary body 116 outwardly away from the equator of the lens 108,generally in the plane 130 of the equator 110 of the lens 108. Thesclera 102 is preferably expanded approximately in the plane of theequator of the lens 108. However, any expansion of the sclera 102 in theregion of the ciliary body 116, i.e., in the region of the sclerasomewhat anterior or posterior to the plane of the equator 110 of thelens 108 is within the scope of the invention, provided that suchexpansion of the sclera 102 moves the ciliary body 116 away from theequator 110 of the lens 108. Typically, the expansion of the sclera willbe accomplished in the region from about 1.5 millimeters anterior to theplane 130 of the equator of the lens 108 to about 2.5 millimetersposterior to that plane, i.e., from about 0.5 millimeters to about 4.5millimeters posterior to the limbus 106. Accordingly, the anteriormargin 122 of a scleral pocket 120 will be located in that region of thesclera.

The prosthesis of the invention is designed to apply an outwardlydirected traction to the sclera at the general position of the anteriormargin 122 of a scleral pocket 120. Accordingly, the prosthesis has anelongated body with a first surface and a second surface each adapted tocontact the base of the scleral pocket or the flap of the scleralpocket. The surfaces are spaced apart by the body of the prosthesis by adistance sufficient to cause the flap to exert an outward traction on atleast the anterior margin of the scleral pocket, with the effect on theadjacent sclera and ciliary body as discussed above.

Although the surfaces can have any suitable shape that accomplishes thepurpose of the prosthesis, it is generally preferred that the prosthesishave a base having one major surface adapted to contact a major portionof the base or flap of the scleral pocket. The base typically has anelongated planform and is oriented generally circumferentially withrespect to the circle defined on the sclera by the intersectiontherewith of the plane 130 of the equator 110 of the lens 108.

The second, opposite, surface of the scleral prosthesis may berelatively broad in an antero-posterior dimension, or it may have arelatively narrow ridge extending along at least a substantial portionof the elongated planform. The prosthesis may be implanted within thescleral pocket or may extend beyond at least one end of the scleralpocket. It is preferable that the prosthesis be of a sufficient lengthto extend beyond the ends of the scleral pocket and contact the outersurface of the intact sclera.

The position of one embodiment of the prosthesis within a scleral pocketand its operation to expand the sclera are illustrated in FIGS. 4 and 5,showing a prosthesis of the type illustrated in FIGS. 6-8.

The base member 202 of the prosthesis 200 has a smooth exterior face 216adapted to be placed in contact with the internal surface of the outerwall 128 of the scleral pocket 120. The opposite, or interior, face 212of the prosthesis 200 is provided with a ridge 214 extending along asubstantial portion of the length of the base 202. This ridge bearsagainst the inner wall 126 of the scleral pocket 120. Accordingly, thesclera 102 at the anterior margin 122 of the scleral pocket 120 iselevated above its original level. The attached ciliary body 116 isthereby also expanded away from the equator 110 of the lens 108, and theworking distance of the ciliary muscle is increased.

A first embodiment of the prosthesis of the invention is illustrated inFIGS. 6-8. FIG. 6 shows a plan view of the inner face of the prosthesis200 having a base 202 with an anterior edge 204, a posterior edge 206,and lateral ends 208 and 210. The inner face 212 is provided with aridge 214 extending along the length of the major dimension of theelongated base 202. FIG. 7 shows a front elevational view of theprosthesis of FIG. 6 showing the flat, smooth outer surface 216 of theprosthesis. FIG. 8 shows a side view of the prosthesis showing the outersurface 216, the ridge 214 and a notch 218 on the inner surface 212 ofthe prosthesis.

FIGS. 9-10 illustrate a prosthesis of the invention having a curvedplanform adapted to be implanted in a scleral pocket that is curved tomatch the curvature of the eyeball. The prosthesis 300 of FIGS. 9-10 hasa generally planar base 302, curved in the plane of the base 302, havingan anterior edge 304, a posterior edge 306, and lateral ends 308 and310. The inner face is provided with a ridge 314 extending along thelength of the major dimension of the elongated curved base 302. FIG. 10shows an end view of the prosthesis of FIG. 9 showing the outer face316, the ridge 314 and a notch 318 on the inner face 312 of theprosthesis. The curvature of the base is chosen to provide at least anapproximate match for the curvature of the adjacent structures on thesurface of the sclera, e.g., the limbus 106, adjusted for the distanceof the scleral pocket 120 and prosthesis 300 from the limbus 106. FIG. 3shows a front elevational view of an eye provided with curved scleralpockets 120 to accommodate a curved prosthesis 300 of the typeillustrated in FIGS. 9 and 10.

FIGS. 11-13 show an embodiment of the invention wherein the anteriorportion is tapered from the ridge to the anterior edge. FIG. 11 shows aplan view of the prosthesis 400 having a base 402 with an anterior edge404, a posterior edge 406, and lateral ends 408 and 410. The outer face416 is smooth and adapted to be placed against the inner surface of theouter wall 128 of a scleral pocket 120. The inner face 412 is providedwith a ridge 414 extending along the length of the major dimension ofthe elongated base 402. FIG. 12 shows a front elevational view of theprosthesis of FIG. 11 showing the flat, smooth outer face 416 of theprosthesis. FIG. 13 shows an end view of the prosthesis of FIG. 11showing the outer face 416 and the ridge 414 on the inner face 412 ofthe prosthesis 400. In this embodiment the ridge 414 tapers toward theanterior edge 404 of the prosthesis.

FIGS. 14-16 show a preferred embodiment of the prosthesis in which theridge member includes extensions beyond the ends of the base memberwhich lie on the surface of the sclera adjacent to the scleral pocketand help to stabilize the prosthesis. FIG. 14 shows a plan view of thisembodiment 500 having a base 502 with an anterior edge 504, a posterioredge 506, and lateral ends 508 and 510. The inner face 512 is providedwith a ridge 514. The ends 508 and 510 of the ridge 514 extend slightlybeyond the ends of the base 502. Accordingly, the ends 508 and 510 ofthe ridge 514 will extend beyond the ends of the pocket 120 and lie onthe surface of the sclera 102. FIG. 15 shows a front elevational view ofthe prosthesis of FIG. 14 showing the flat, smooth outer face 516 of theprosthesis and the ends 508 and 510 of the ridge 514 extending beyondthe ends of the base 502. FIG. 16 a shows an end view of the prosthesisof FIG. 14 showing the smooth outer face 516 and the ridge 514 on theinner face 512 of the base 502, as well as a notch 518. FIG. 16 b showsan end view of an alternate embodiment of the prosthesis 500 wherein thebase 502 does not taper all the way to the posterior edge 506.Evidently, the thickness of the posterior edge 506 may vary from arelatively sharp posterior edge as shown in FIG. 16 a to a relativelythick posterior edge as shown in FIG. 16 b, or even thicker if it isadvantageous.

FIGS. 17-20 illustrate an embodiment of the prosthesis that is hollowand made from a plastic or elastomeric material and filled with aliquid. FIG. 17 shows a plan view of this embodiment 600 having a base602 with an anterior edge 604, a posterior edge 606, and lateral ends608 and 610. The inner face 612 is smoothly rounded and rises to a crest614 that serves to support the prosthesis on the inner wall 126 of thescleral pocket 120 in the same way as the ridge member of otherembodiments of the invention. FIG. 18 shows a front elevational view ofthe prosthesis of FIG. 17 showing the flat, smooth outer face 616 of theprosthesis. FIG. 19 shows a cross section of the prosthesis of FIG. 17taken along the line 19-19. The cross-section shows the flexible wall612 of the prosthesis as well as the flat outer face 616, and the crest614. The cross section also shows the filling liquid 620. FIG. 20 showsan end view of the prosthesis of FIG. 17 showing the outer face 616 andthe crest or ridge 614 on the inner face 612 of the prosthesis 600. Thehollow prosthesis is filled with liquid, typically by injecting theliquid through an end 608 or 610. The prosthesis may be filled with moreor less liquid in order to adjust the thickness between the outer face616 and the crest or ridge 614 to provide more or less traction on thesclera at the anterior margin 122 of the scleral pocket or belt loop120.

FIGS. 21-23 illustrate an embodiment of the invention generally similarto that shown in FIGS. 6-8, having, however, a base in which the innerface of the prosthesis is curved to provide an approximate match to thecurvature of the globe. FIG. 21 shows a plan view of the inner face ofthe prosthesis 700 having a base 702 with an anterior edge 704, aposterior edge 706, and lateral ends 708 and 710. The inner face 712 isprovided with a ridge 714 extending along the length of the majordimension of the elongated base 202. FIG. 22 shows a front elevationalview of the prosthesis of FIG. 21 showing the curved, smooth outersurface 716 of the prosthesis. FIG. 23 shows an end view of theprosthesis showing the outer surface 716, the ridge 714 and a notch 718on the curved inner surface 712 of the prosthesis.

A preferred embodiment of the scleral prosthesis is that shown in FIGS.9 and 10, wherein the anterior rim 304 and the posterior rim 306 areboth generally circular arcs. The taper in the diameter of the segmentis preferably selected in an individual case to fit the globe in theregion of the ciliary body. Accordingly, different sizes of segmentswill be provided wherein the radius of curvature of the anterior rimranges from about 7.0 to about 10 millimeters in 0.50 millimeterincrements. Accordingly, a preferred segment has a typical internalcircular radius of curvature at its anterior portion of about 7.76millimeters, at the position of the ridge of about 8.21 millimeters, andat the posterior rim of about 8.91 millimeters. The preferred segmenthas outer radius of curvature at its anterior portion of 8.02millimeters, at its mid portion 8.47 millimeters, and at its base 8.94millimeters. These measurements will vary depending on the size of theeye, the amount of rigidity required, and the strength of the materialfrom which the segment is made. The preferred anterior chord length ofthe segment is 5 millimeters. The axial width of the segment willtypically be about 2 millimeters.

FIGS. 24-27 illustrate another preferred embodiment 800 of the scleralprosthesis of the invention having a curved surface to contact the base126 of the scleral pocket and an elevated ridge or opposite surface tocontact the inner side 128 of the flap of the scleral pocket 120. Thisembodiment 800 has a base 802 having a smooth surface 816. Theprosthesis 800 has an anterior edge 804 and posterior edge 806, whichare relatively flat surfaces as shown. Opposite the base surface 816 isan elevated surface or ridge 814. In the illustrated embodiment theelevated surface or ridge 814 is relatively broad in anantero-posterior, or axial, dimension. However, the ridge 814 may berelatively narrower or broader than shown. The prosthesis 800 haslateral ends 808 and 810. The prosthesis 800 is shown as having a curvedbase surface 816. The surface 816 may also be flat or straight in thetransverse dimension. However it is preferred that the surface 816 becurved as shown to generally match the curvature of the sclera in thezone adjacent to and contiguous with the ciliary body.

The position of the scleral prosthesis 800 when implanted in an eye isshown in the anterior elevational view of an eye, FIG. 28. FIG. 29 showsa cross-section of the eye shown in FIG. 28, along the line 29-29,showing the prostheses 800 in place in the scleral pockets 120. FIG. 30shows an enlarged detail of the prosthesis 800 in the region defined bythe circle 30 in FIG. 29.

The height of the prosthesis between base surface 816 and ridge 814 ispredetermined to elevate the flap of the scleral pocket or belt loop 120sufficiently to exert an outwardly directed traction on at least theanterior margin 122 of the scleral pocket that is sufficient to elevatethe sclera adjacent to the anterior margin 122 by an amount sufficientto accomplish the purpose of the invention, i.e., to increase theworking distance of the ciliary muscle and thereby restore the amplitudeof accommodation of the presbyopic eye. Typically, the distance betweenthe major surface 816 and the second surface or ridge 814 will be in therange of from about 0.3 millimeters to about 0.9 millimeters, preferablyfrom about 0.5 millimeters to about 0.7 millimeters, and most preferablyabout 0.6 millimeters. The antero-posterior dimension of the prosthesis800, as measured between the surfaces 804 and 806 in the illustratedembodiment, may range from about 0.3 millimeters to about 0.9millimeters, preferably from about 0.5 millimeters to about 0.7millimeters, and most preferably about 0.6 millimeters. It will beunderstood by those skilled in the art that the distances between thesurface 816 and ridge 814 and between anterior edge or surface 804 andposterior edge or surface 806 may be varied as appropriate to fit in ascleral pocket of defined dimensions. These dimensions are chosen toaccomplish the purpose of the invention, i.e., to produce an elevationof the sclera and associated ciliary body as discussed above.Consequently the actual cross sectional shape of the prosthesis may varyform that shown in FIGS. 24-27. The length of the scleral prosthesis800, which may be referred to as the transverse dimension as implantedin an eye, is chosen to provide an outward traction along a sufficientlength of the circumference of the sclera of the eye in the zoneencompassing the ciliary body to provide an effective amount ofelevation of the sclera and attached ciliary body to accomplish thepurpose of the invention. The length chosen will also depend on whetherthe surgeon prefers to implant the prosthesis entirely within the lengthof the scleral pocket 120, or have the ends of the prosthesis extendbeyond the ends of the scleral pocket, as shown in FIG. 28. It ispreferred to have the ends 808, 810 of the prosthesis 800 extend beyondthe lateral ends of the scleral pockets or belt loops, as shown in FIG.28. When the prosthesis 800 is so dimensioned and positioned, the ends808, 810 bear on the intact sclera adjacent to the ends of the scleralbelt loops to enhance the outward force exerted on the outer flap of thescleral pocket or belt loop 120. Typically the transverse dimension ofthe prosthesis will range from about 3.0 millimeters to about 8.0millimeters, preferably from about 3.5 millimeters to about 6.0millimeters, more preferably from about 4.0 millimeters to about 5.0millimeters, and most preferably about 4.5 millimeters. It will beunderstood by the skilled practitioner that the dimensions of theprosthesis are adapted to the dimensions of the individual eye in whichthey are implanted, the dimensions being chosen to achieve an effectiveincrease in the diameter of the sclera in the zone of the scleraadjacent to the ciliary body to produce an accompanying increase in thediameter of the ciliary body to provide an effective treatment forpresbyopia and the other eye disorders discussed herein. As aconsequence of the possible variations in the dimensions of theprosthesis in the inner-outer (or height) dimension, theantero-posterior dimension, and the length or transverse dimension, theexact shape of the prosthesis may vary significantly from that shown inFIGS. 24-27. The dimensions and exact shape of the prostheses are to beadapted to the eye in which they are to be implanted. Ordinarily aplurality, preferably four prostheses are implanted as shown in FIGS. 2,3, and 28. However, more or fewer prostheses can be implanted.Ordinarily, all the prostheses implanted in one eye will be identical,but it is not excluded that prostheses of different shapes anddimensions may be implanted to achieve results desired by the surgeon.

The scleral prosthesis of the invention is made of a material that issufficiently rigid to exert a force on the sclera sufficient to producethe radial expansion required by the method of the invention and that isphysiologically acceptable for long-term implantation or contact withthe ocular tissues. Such materials are well-known in the surgical artand include suitable metals, ceramics, and synthetic resins. Suitablemetals include titanium, gold, platinum, stainless steel, tantalum andvarious surgically acceptable alloys, and the like. Suitable ceramicsmay include crystalline and vitreous materials such as porcelain,alumina, silica, silicon carbide, high-strength glasses and the like.Suitable synthetic materials include physiologically inert materialssuch as poly (methyl methacrylate), polyethylene, polypropylene,poly(tetrafluoroethylene), polycarbonate, silicone resins and the like.The prosthesis may also be made of composite materials incorporating asynthetic resin or other matrix reinforced with fibers of high strengthmaterial such as glass fibers, boron fibers or the like. Thus, thesegment may be made of glass-fiber-reinforced epoxy resin, carbonfiber-reinforced epoxy resin, carbon fiber-reinforced carbon(carbon-carbon), or the like. The segment may be made of a semi-rigidexterior and a liquid or gel filled interior so that the internal andexternal dimensions can be altered by injecting various amounts ofliquid: water, saline, or silicone oil; or various amounts of a gel:silicone, collagen, or gelatin. The semi-rigid exterior may be made ofany of the already listed materials. It will also be understood by theskilled practitioner that the material of which the scleral prosthesisis made may be adapted to the particular shape or design chosen for theprosthesis. For example, a prosthesis such as that shown in FIGS. 17-20may be made of a material that can deflect and stretch under theinternal pressure of the liquid or the like with which it is filled,whereas a prosthesis of the type shown in FIGS. 24-28, which receivessupport from regions of the intact sclera adjacent to the ends of thescleral pockets or belt loops may preferably be made of a relativelyrigid material. A preferred material for the entire segment is surgicalgrade poly(methyl methacrylate).

The scleral prosthesis of the invention may be manufactured by anyconventional technique appropriate to the material used, such asmachining, injection molding, heat molding, compression molding and thelike.

The scleral prosthesis may be foldable to facilitate insertion into ascleral belt loop or made in a plurality of parts so that it can beassembled prior to use or may be installed separately to form a completeprosthesis.

In practicing the method of the invention, the surgeon locates theproper region of the sclera to be expanded by measuring a distance ofpreferably 2.0 millimeters posterior of the limbus. At 2.5 millimetersclockwise and counterclockwise from each of the 45° meridians of theeye, and 2 millimeters posterior to the limbus, partial scleralthickness radial incisions, i.e., antero-posterior incisions, are madewhich are 2 millimeters long and 350 microns deep. Using a lamella bladethe sclera is dissected until the partial thickness incisions areconnected so that four scleral pockets or belt loops are made which havean anterior length of 5 millimeters, and a length extending generallyaxially of the eye of 2 millimeters. Thus, each pocket or belt loop ispreferably centered over the 45° meridian of the eye. A prosthesis isthen inserted in each of the four scleral belt loops. This producessymmetrical scleral expansion which will produce the desired result ofincreasing the effective working distance of the ciliary muscle.

The location of the prostheses of the invention when implanted in theeye is illustrated in FIGS. 1-4. FIG. 1 is an isometric view of an eye100 having a globe 102 with the relevant exterior anatomical partsindicated as discussed above.

FIGS. 2 and 3 show front elevational views of an eye 100 showing thescleral pockets 120 formed at approximately the 45° meridians of theeye, i.e., approximately halfway between the vertical and horizontalmeridians of the globe. This location is preferred because it avoidsinterference with structures of the eye that are located generally onthe vertical and horizontal meridians. FIG. 3 shows the use of curvedscleral pockets 120 to permit the use of curved prostheses of the typeillustrated in FIGS. 9 and 10. FIG. 2 shows the use of straight scleralpockets 120. Such straight pockets are somewhat simpler to preparesurgically: For many patients the use of straight prostheses can provideadequate treatment of their presbyopia.

FIG. 4 shows a cross-section of the eye, taken along the line 4-4 inFIG. 3, showing the placement of the prosthesis of the inventionrelative to the significant anatomical structures of the eye. Thisfigure shows the general configuration of the scleral pockets 120 andthe prostheses 200 of the type illustrated in FIGS. 6-8 in a preferredembodiment. The anterior margins 122 of the scleral pockets or beltloops 120 are located approximately in the plane 130 of the equator 110of the lens 108. The ridge 210 of the prosthesis causes the anteriorportion of the pocket to be expanded somewhat more than the posteriorportion. This places the sclera at the anterior margin of the pocketunder a radial tension and causes it to expand somewhat from its normaldiameter at that position. This scleral expansion draws with it theunderlying ciliary body 116 and causes the ciliary body to be drawn awayfrom the equator 110 of the lens 108. Accordingly, the expansion of theciliary body 116 operates to increase the working distance of theciliary muscle and restore, at least in part, the ability of the eye toaccommodate for clear focusing on objects at different distances. FIG. 5shows an enlarged portion of one of the scleral pockets 120 withadjacent anatomical structures. It shows the relation of the scleralpocket 120 to the underlying structures and its location just posteriorto the equator of the lens 108 and overlying the ciliary body 116.

The method of the invention which increases the amplitude ofaccommodation may also be of benefit in treatment of hyperopia incertain patients. Some youthful hyperopes can achieve relatively normalvision by compensating for their hyperopia through the naturalaccommodative ability of the eye. However, as this ability declines withage, they find that it becomes more difficult to attain normal vision bythis process, and they begin to experience headaches and other symptoms,even at an age somewhat less than usual for the onset of presbyopia.Evidently, increasing the amplitude of accommodation by the method ofthis invention would be useful in restoring the ability of thesepatients to compensate for their hyperopia.

The method of this invention also has utility in the treatment ofprimary open-angle glaucoma, which shows a correlation with age incertain individuals. It has been found that, in general, intraocularpressure (IOP) exhibits a linear increase with increasing age. (Armaly,M.F., On the distribution of applanation pressure I. Statisticalfeatures and the effect of age, sex, and family history of glaucoma,Archives of Ophthalmology, Vol. 73, pp. 11-18 (1965)). Among the generalpopulation is found a group of individuals who develop abnormally highintraocular pressures as a result of primary open angle glaucoma, adisease which is one of the most prevalent causes of blindness in theworld. According to the theory of this invention, the linear increase inIOP with age is a direct result of the decrease in distance between thelens equator and the ciliary muscle and the resulting linear decrease inthe effective pull of the ciliary muscle. Since the ciliary muscleinserts into the trabecular meshwork, the decrease in pull will decreasethe size of the trabeculum and/or the drainage pores and result in alinear increase of intraocular pressure with age. In this view, thepatients who develop primary open angle glaucoma may have a congenitalpredilection to narrower pores, protein deposition in the pores, and/ora smaller trabecular meshwork, so that when the ability of the ciliarymuscle to exert force declines, after the age of 40 or thereabouts, theytend to develop excessively elevated IOP.

The method of the invention which increases the effective workingdistance of the ciliary muscle, and thereby increases the force that itcan exert when it contracts, restores the level of force which theciliary muscle exerts on the trabecular meshwork to a valuecharacteristic of a more youthful eye. In this way it is expected thatthe tendency of an eye that is disposed to develop primary open angleglaucoma as it ages would be overcome and the onset of this diseasewould be prevented or at least postponed.

The invention having now been fully described, it should be understoodthat it may be embodied in other specific forms or variations withoutdeparting from its spirit or essential characteristics. Accordingly, theembodiments described above are to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than the foregoing description,and all changes which come within the meaning and range of equivalencyof the claims are intended to be embraced therein.

1. An ocular scleral prosthesis comprising: an elongated body adapted to be implanted in an elongated pocket surgically formed within scleral tissue of an eye in a zone of a globe of the eye exterior to a ciliary body of the eye, the pocket having (i) a base comprised of inner layers of the scleral tissue, (ii) a flap formed from outer layers of the scleral tissue, (iii) an anterior margin and (iv) a posterior margin, wherein the elongated body is non-circular and has a first free end and a second free end, wherein the elongated body also has a first surface and a second surface opposite the first surface, the first surface and the second surface being adapted to respectively contact the base and the flap of the scleral pocket when the prosthesis is implanted, wherein one of the first and second surfaces is planar, and wherein the other of the first and second surfaces comprises a ridge or a crest separated from the planar surface by a distance sufficient to elevate the flap relative to the base and exert outwardly directed traction on at least the anterior margin of the pocket when the prosthesis is implanted in order to at least one of: increase a working distance of a ciliary muscle of the eye and increase an amplitude of accommodation of the eye.
 2. The ocular scleral prosthesis set forth in claim 1 wherein: the elongated body comprises a planform having a longer first dimension and a shorter second dimension; and the elongated body is curved along the first dimension.
 3. A prosthesis adapted for contact with a sclera of an eyeball, the prosthesis comprising: an elongated body having a first free end and a second free end, wherein the first free end is more distal from the second free end than from any other portion of the elongated body, and wherein the first and second free ends are adapted to be unattached to any other prosthesis when the prosthesis is implanted, the elongated body including a first surface and a second surface opposite the first surface, the first surface and the second surface each adapted to contact a portion of the sclera when the prosthesis is implanted; and means for expanding the contacted sclera, when the prosthesis is implanted, to increase an effective working distance of a ciliary muscle of the eyeball; wherein one of the first and second surfaces is planar, and the means for expanding comprise a ridge or a crest on the other of the first and second surfaces.
 4. The prosthesis set forth in claim 3 wherein at least one of the first surface and the second surface is generally smooth and is adapted to contact ocular tissue within a pocket surgically formed within the sclera of the eyeball when the prosthesis is implanted.
 5. The prosthesis set forth in claim 3 wherein the prosthesis is at least one of generally rectangular, curved, and elongated.
 6. The prosthesis set forth in claim 3 wherein at least one of the first surface and the second surface comprises an anterior edge and a posterior edge, and the ridge or crest has a maximum height above the elongated body at one of: (i) a location intermediate between the anterior edge and the posterior edge, (ii) a location less than halfway from the anterior edge to the posterior edge, and (iii) a location at the anterior edge.
 7. The prosthesis set forth in claim 3 wherein the elongated body comprises a planform having a longer first dimension and a shorter second dimension.
 8. The prosthesis set forth in claim 7 wherein the ridge or crest extends along at least a portion of the first dimension.
 9. The prosthesis set forth in claim 7 wherein the first dimension is about five (5) millimeters and the second dimension is about two (2) millimeters.
 10. The prosthesis set forth in claim 7 wherein the elongated body is curved along the first dimension.
 11. The prosthesis set forth in claim 3 wherein the prosthesis is made of at least one of a physiologically acceptable metal, a ceramic material, a synthetic resin, a reinforced composite material, and a flexible material.
 12. The prosthesis set forth in claim 3 wherein the prosthesis is provided with an internal cavity.
 13. The prosthesis set forth in claim 12 wherein the internal cavity is filled with at least one of a fluid and a gel.
 14. The prosthesis set forth in claim 12 wherein the internal cavity is filled with at least one of water, a saline solution, an oil, silicone, collagen, and gelatin.
 15. A prosthesis for surgical implantation into a pocket in a sclera of an eyeball, the prosthesis comprising an elongated body having a first free end and a second free end, both ends adapted to be free of contact with any other prosthesis when the prosthesis is implanted, wherein the elongated body has no portions that are spaced apart from each other further than the first and second free ends, wherein the elongated body includes a first surface and a second surface, the first surface and the second surface being adapted to contact the sclera when the prosthesis is implanted, wherein one of the first and second surfaces is planar and the other of the first and second surfaces comprises a ridge or a crest separated from the planar surface so as to apply an outward force on the scleral pocket when the prosthesis is implanted to elevate an overlying portion of the sclera to increase an effective working distance of a ciliary muscle of the eyeball.
 16. The prosthesis set forth in claim 15 wherein the elongated body is generally rectangular.
 17. The prosthesis set forth in claim 15 wherein the elongated body is arched along a long dimension thereof.
 18. The prosthesis set forth in claim 15, wherein at least one of the first surface and the second surface comprises an anterior edge and a posterior edge, and the ridge or crest has a maximum height located intermediate between the anterior edge and the posterior edge.
 19. The prosthesis set forth in claim 15, wherein at least one of the first surface and the second surface comprises an anterior edge and a posterior edge, and the ridge or crest has a maximum height located between the anterior and posterior edges less than halfway from the anterior edge toward the posterior edge.
 20. The prosthesis set forth in claim 15, wherein the elongated body has a planform having a first dimension longer than a second dimension, wherein at least one of the first surface and the second surface is adapted to contact the sclera along the second dimension when the prosthesis is implanted.
 21. A scleral prosthesis comprising a body adapted for contact with a sclera of an eye in a region of a ciliary body when implanted, the body being non-circular and having a first free end, a second free end, and a ridge or a crest projecting above surrounding portions of the body, the ridge or crest located between first and second edges of the body and extending along at least a majority of a length of the body from the first free end to the second free end, the ridge or crest adapted to exert a force with respect to the contacted eye to expand the sclera in the region of the ciliary body when the prosthesis is implanted; wherein the ridge or crest is configured, when the prosthesis is implanted, to at least one of: increase a working distance of a ciliary muscle of the eye and increase an amplitude of accommodation of the eye.
 22. The scleral prosthesis set forth in claim 21 wherein the ridge or crest is configured to exert the force to increase the working distance of the ciliary muscle of the eye.
 23. The scleral prosthesis set forth in claim 21 wherein the ridge or crest is configured to exert the force to increase the amplitude of accommodation of the eye.
 24. The scleral prosthesis set forth in claim 21 wherein the body further has an outer surface that is adapted to contact ocular tissue within a pocket surgically formed within the sclera of the eye.
 25. The scleral prosthesis set forth in claim 24 wherein the body further has a base adapted to contact scleral tissue between anterior and posterior margins of the pocket when the prosthesis is implanted within the pocket, the base adapted to contact the scleral tissue along a width of the base when the prosthesis is implanted.
 26. The scleral prosthesis set forth in claim 21 wherein the prosthesis has a generally rectangular planform.
 27. The scleral prosthesis set forth in claim 21 wherein the body further comprises a planform having a first dimension longer than a second dimension, a first surface and a second surface, and a height, the ridge or crest formed by or projecting from the first surface, the second surface adapted to contact sclera tissue across the planform when the prosthesis is implanted within a pocket surgically formed within the sclera of the eye.
 28. The scleral prosthesis set forth in claim 27 wherein the second surface is planar.
 29. The scleral prosthesis set forth in claim 27 wherein the body comprises the ridge, the ridge extending along at least a portion of the first dimension of the body and formed by an intersection of a first portion of the first surface that extends substantially along the height of the body with a second portion of the first surface that slopes across both the planform and the height.
 30. The scleral prosthesis set forth in claim 27 wherein the first dimension is about five millimeters and the second dimension is about two millimeters.
 31. The scleral prosthesis set forth in claim 27 wherein the second surface is curved along the first dimension.
 32. The sclera prosthesis set forth in claim 27 wherein the ridge or crest extends along at least a portion of the first dimension of the body.
 33. The scleral prosthesis set forth in claim 21 wherein the prosthesis is made of at least one of a physiologically acceptable metal, a ceramic material, a synthetic resin, a reinforced composite material and a flexible material.
 34. The scleral prosthesis set forth in claim 21 wherein the prosthesis is provided with an internal cavity.
 35. The sclera prosthesis set forth in claim 34 wherein the internal cavity is filled with at least one of a fluid and a gel.
 36. The scleral prosthesis set forth in claim 34 wherein the internal cavity is filled with at least one of water, a saline solution, an oil, silicone, collagen, and gelatin.
 37. A scleral prosthesis comprising a body adapted for contact with a sclera of an eye in a region of a ciliary body, the body being non-circular and having: (i) a base member having an elongated planform with a major dimension, a minor dimension, an inner major surface and a planar outer major surface, the body being adapted to contact ocular tissue of the eye in the region of the ciliary body when the prosthesis is implanted, and (ii) a ridge or crest member on the inner major surface of the base member and along the major dimension of the base member and spaced apart from edges of the base member, wherein the ridge or crest member is adapted, when the prosthesis is implanted in the eye, to apply a force to the contacted ocular tissue to thereby expand the sclera in the region of the ciliary body, wherein the ridge or crest member is adapted to apply the force to the contacted ocular tissue when the prosthesis is implanted at a location spaced apart from any other prosthesis; and wherein the ridge or crest member is configured, when the prosthesis is implanted, to at least one of: increase a working distance of a ciliary muscle of the eye and increase an amplitude of accommodation of the eye.
 38. The sclera prosthesis set forth in claim 37 wherein the ridge or crest member is configured, when the prosthesis is implanted in the eye, to exert the force to increase the working distance of the ciliary muscle of the eye.
 39. The scleral prosthesis set forth in claim 37 wherein the ridge or crest member is configured, when the prosthesis is implanted in the eye, to exert the force to increase the amplitude of accommodation of the eye.
 40. The scleral prosthesis set forth in claim 37 wherein the outer major surface is adapted to contact the ocular tissue within a pocket surgically formed within the sclera of the eye.
 41. The scleral prosthesis set forth in claim 37 wherein the prosthesis is generally rectangular.
 42. The scleral prosthesis set forth in claim 37 wherein the base member has an anterior edge and a posterior edge, wherein the ridge or crest member is located spaced apart from the anterior edge.
 43. The scleral prosthesis set forth in claim 37 wherein the major dimension is about five millimeters and the minor dimension is about two millimeters.
 44. The scleral prosthesis set forth in claim 37 wherein the prosthesis is made of at least one of a physiologically acceptable metal, a ceramic material, a synthetic resin, a reinforced composite material and a flexible material.
 45. The scleral prosthesis set forth in claim 37 wherein the prosthesis is provided with an internal cavity.
 46. The scleral prosthesis set forth in claim 45 wherein the internal cavity is filled with at least one of a fluid and a gel.
 47. The scleral prosthesis set forth in claim 45 wherein the internal cavity is filled with at least one of water, a saline solution, an oil, silicone, collagen, and gelatin.
 48. The prosthesis set forth in claim 37 wherein the body is curved along the major dimension.
 49. A prosthesis that contacts a sclera of an eyeball, the prosthesis comprising a non-circular body having a first free end and a second free end spaced apart from the first free end such that no portion of the body overlaps any other portion of the body, the body also having a planform that is adapted to expand the contacted sclera and that includes top and bottom surfaces, one of the top and bottom surfaces being planar and the other of the top and bottom surfaces comprising a ridge or a crest separated from the planar surface so as to increase an effective working distance of a ciliary muscle of the eyeball, wherein each of the first and second free ends lacks a mechanism for coupling to an end of another prosthesis.
 50. The prosthesis set forth in claim 49 wherein the top surface is adapted to contact ocular tissue within a pocket surgically formed within the sclera of the eyeball.
 51. The prosthesis set forth in claim 50 wherein the top surface is circumferentially shaped and is adapted to exert an outward force on the scleral pocket to elevate a portion of the sclera attached thereto to increase the effective working distance of the ciliary muscle of the eyeball.
 52. The prosthesis set forth in claim 50 wherein the body further comprises a means for stabilizing the prosthesis within the scleral pocket.
 53. The prosthesis set forth in claim 52 wherein the stabilizing means includes the bottom surface that is adapted to contact ocular tissue within the scleral pocket.
 54. The prosthesis set forth in claim 53 wherein an ocular tissue contact area of the bottom surface of the body is at least substantially equal to an ocular tissue contact area of the top surface of the body.
 55. The prosthesis set forth in claim 52 wherein the stabilizing means includes at least one of the first end and the second end that is adapted to fix the body within the scleral pocket. 